An optical semiconductor device is a device that converts electric energy into light energy, and includes, for example, a light emitting diode (LED). An LED can emit light at various wavelengths depending on light emitting materials, and includes, for example, organic LEDs, inorganic LEDs, quantum dot LEDs, and the like. Such an LED has advantages such as high photo-conversion efficiency, low energy consumption, long lifespan, and environmental friendliness, and thus is used as a light source of an illumination device.
Examples of an illumination device using an LED as a light source include a light source including a diode, a package, a panel, and a module, and also include a component including a reflector, a housing, a light guide plate, and a light diffusion plate to increase photo-availability. A material for the component is required to exhibit high reflectance, heat resistance, and discoloration resistance.
Recently, as such a material for the component, a polyester resin having excellent deformation resistance and discoloration resistance at high temperature has been used. There remains a need, however, for a technique capable of improving mechanical strength, heat resistance, moldability, and reflectance of a polyester thermoplastic resin, which is used as a material for components of an LED illumination device.